1. Field
The invention relates to the type of acid gas burner and reactor apparatus shown in Shumaker U.S. Pat. No. 3,782,884 of Jan. 1, 1974 as improved by Desmond H. Bond et al. in accordance with U.S. Pat. No. 3,963,443 of Jun. 15, 1976, both of these sets of apparatus intended primarily for use in connection with practice of the well-known Claus process for producing elemental sulfur from hydrogen sulfide gas. State
2. State of the Art
The Claus process was developed in Germany many years ago and has been used throughout the world for extracting sulfur from hydrogen sulfide (H2S) effluent gases to both recover elemental sulfur therefrom and reduce the atmospheric polluting character of such gases.
In carrying out""the process, the H2S gas, air, and fuel gas, are fed into the burner part of""the apparatus for combustion at a very high temperature in a reaction chamber part of the apparatus such that one-third of the volume of the acid feed gas is converted into sulfur dioxide (SO2). The products of combustion are normally passed through a catalyst to effect the following reaction:
2H2S+SO2=3S+2H2O.
However, close flow control and metering of the reactants and thorough mixing thereof prior to and during combustion are very important procedural considerations in practice of the process. Accordingly, prime structural features of acid gas burner and reactor apparatus for the purpose have been those ensuring maximum flow control and effective mixing of the reactants as they pass through the burner into the reaction chamber.
The Bond et al. acid gas burner and reactor apparatus, as produced and sold by an affiliate of the engineering firm of Ford, Bacon and Davis, Dallas, Tex., was a significant improvement on earlier acid gas burner and reactor apparatus, including the Shumaker acid gas burner and reactor apparatus, and has been used throughout the world primarily in connection with practice of the Claus process.
The Bond et al. acid gas burner and reactor apparatus improved the earlier acid gas burner and reactor apparatus and was eminently successful because it fed a multitude of jets of the hydrogen sulfide gas into a centrally flowing stream of air from a surrounding annular stream of the gas through a corresponding multitude of so-called nozzle apertures arranged in a series of annular rows extending along the streams of air and gas. Superior mixing of the gas with the air for the Claus reaction was obtained and certain difficulties, brought about by the Shumaker and earlier constructions, were overcome. Thus, Shumaker""s burner tube cap,. that was adjustable closer to or farther away from the open discharge end of the H2S-gas-carrying conduit by means of a longitudinally movable shaft carrying such cap at one of its ends, to provide a size adjustable, annular slot as a discharge opening leading into a surrounding flow of air for metering and controlling the quantity of H2S gas being mixed with air as it discharges into the reaction chamber of the apparatus, was replaced by longitudinally successive, circular rows of jet openings, each such row being in the form of a multitude of closely spaced and relatively small nozzle apertures leading, contrary to Shumaker, into a centralized flow of air from a surrounding flow of the H2S gas.
I have developed an acid gas burner and reaction apparatus that is an improvement over both the earlier Shumaker apparatus and the later Bond et al. apparatus in that it provides greater versatility in flow rates, while insuring: better mixing; that it substantially eliminates or at least minimizes unwanted side reactions of SO3 with other components, such as ammonia, which produce heat stable salts tending to plug downstream equipment; and that it thereby achieves longer on-stream time, produces a higher ratio of acid gas to oxidant gas, permits better control of the ratio of these two gases over a wide flow range, decreases maintenance expense, makes for higher recovery of sulfur accompanied by fewer emissions, and achieves cost savings in manufacture of the apparatus.
I have found that retaining an annular curtain flow of the H2S gas into the airstream, according to Shumaker and earlier forms of acid gas burners, rather than the Bond et al. multiple jet flows from circular rows of nozzle apertures, but retaining the Bond et al. arrangement of flowing the H2S gas into a centralized flow of air from a surrounding annular stream of the gas, achieves the advantageous results sought. The teachings of the prior art actually lead away from anyone skilled in the art doing what I did in accordance with this present invention.
Thus, my invention principally resides in replacing Bond et al.""s concentric circular rows of nozzle apertures, for producing jets of the H2S gas feeding into the reaction chamber of the apparatus, with the very thing that Bond et al. had earlier so successfully replaced, namely the circular slot that produces annular flow of the H2S gas as in the Shumaker and earlier prior art patents. To do this, I have modified the Bond et al. construction as is herein shown and described.